While conveyors with which the chain of the present invention are intended to be used may have many applications, for purposes of an exemplary showing, such conveyors will be described with respect to their use in the mining industry, although their use is not intended to be so limited.
Pusher-type chain conveyors, as used in the mining industry, are found both in the form of separate conveying units, and as integral parts of continuous mining machines. A typical continuous mining machine, for example, is self-propelled and is provided at its forward end with cutting means shiftable in such a way that an entry is cut in the material being mined. The entry is so sized as to permit the passage of the mining machine therethrough. Since the cutting operation is a continuous one, it is necessary to provide means to move the cut material from in front of the mining machine and to convey it out of the entry. To this end, the mining machine usually incorporates several conveyors in its construction, the conveyors acting successively to transport the cut material rearwardly of the machine. Frequently, the mining machine further incorporates a "tail conveyor" which is a part of the mining machine, located at its rearward end. The purpose of the tail conveyor is to deliver the cut material to other conveying means by which it is removed from the entry. The other conveying means may comprise mine cars, portable belt conveyors, or the like.
The most frequently encountered form of tail conveyor, in association with a continuous mining machine, comprises a section of conveyor base means mounted on the mining machine body. One or more additional sections of conveyor base means are connected thereto end-to-end, and extend beyond the rearward end of the mining machine body. All of the base means sections are characterized by a bottom portion provided with longitudinally extending, upstanding side guides or flanges.
In order for the tail conveyor to perform its task properly, the various sections thereof must be capable of both lateral and vertical movement with respect to each other. This enables the cut material to be delivered to a desired point despite changes of position of the mining machine as it advances in the entry and changes in level of the entry floor. Similarly, this lateral and vertical movement capability of the conveyor sections enables the shifting of the desired delivery point for the material being mined, as required.
The tail conveyor incorporates a continuous pusher-type conveyor chain which is driven along the length of the conveyor base sections. The chain is normally provided with a plurality of rigid pusher elements, normally extending substantially transversely of the conveying direction. The pusher elements are located at spaced intervals along the chain. Adjacent pusher elements are joined together by a series of alternate block-like links and plate-like links. At one end of the tail conveyor, the continuous chain passes over a driven sprocket. At the other end of the conveyor, the chain passes over a driven or idler sprocket, or roller.
From the above description it will be apparent that the conveyor chain must not only be capable of bending in a vertical plane so as to follow the conveyor base sections and to pass over the sprockets, but also it must be capable of bending in a horizontal plane so as to track along the conveyor base sections when they are angularly related, one to another.
Prior art workers have developed numerous types of conveyor chains to meet these requirements. In general, such chains have comprised a plurality of links and interconnecting plates held together by horizontally disposed pintles. The laterally extending pusher elements have been affixed to or formed as a part of selected ones of the chain plates. A number of approaches have been taken to render such chains capable of double articulation (i.e., both vertical and horizontal or lateral). For example, chains have been produced, the parts of which are loosely fitting. Such chains, however, have been characterized by a minimum of horizontal articulation and have generally proven unsatisfactory and subject to excessive wear of the parts.
In another approach, selected ones of the block-like links of the chain have been made in two parts, pivoted to each other by a vertical pintles. Thus, a sort of universal joint is formed enabling the chain to deflect in the horizontal plane. This construction, however, has proven to have numerous drawbacks, including the fact that the necessarily abbreviated length and diameter of the vertical pintles has resulted in chain breakage.
In U.S. Pat. No. 3,155,225, a pusher-type chain is described wherein many of these problems have been overcome. The chain of this patent has special block-like connector links provided at the positions of the pusher elements. These special connector links have, at their adjacent ends, uniquely formed transverse pintle-receiving perforations. The pusher elements each comprise a pair of pushers joined together by a pair of pintles. Each of the pintles joining a pair of pusher elements passes through one of the uniquely formed transverse pintle-receiving perforations of the special connectors. The facing surfaces of the pusher elements of each pair are also specially configured so that the chain is capable of double articulation at the position of each pusher element, with a minimum of lost motion, a minimum of wear and without loss of strength.
U.S. Pat. No. 3,957,153 teaches yet another form of pusher-type conveyor chain with even greater horizontal articulation capabilities at the positions of the pusher elements. This patent teaches a pusher-type chain having pusher elements located at desired intervals along its length and joined together by a series of link elements. Centrally of each pusher element, there are forward and rearward extensions. Each of these extensions is provided with a transverse perforation of particular configuration and adapted to receive a generally U-shaped, strap-like link. Thus, each of the series of links located between adjacent pusher elements terminates at its ends in the above noted U-shaped, strap-like link engaging the adjacent pusher element.
The present invention is based upon the discovery that lateral or horizontal articulation can be achieved in those parts of a pusher-type chain between the pusher elements without the use of loose chain parts, universal joints or link elements made of flexible material. This is accomplished through appropriate configuration of selected ones at least of the pairs of plate-like links together with the pintel holes of adjacent block-like links. The teachings of the present invention can be incorporated in conventional pusher-type chains, or chains of the type taught in the above identified U.S. Pat. Nos. 3,155,225 and 3,957,153. Thus, when incorporated with the chains of the above mentioned patents, the resulting chain will be capable of vertical articulation throughout its length and horizontal articulation both at the pusher elements and therebetween.